1. Field of the Invention
The present invention relates to a giant magnetoresistive effect element and also relates to a magnetoresistive effect type head, a thin-film magnetic memory and a thin-film magnetic sensor, each of which includes this giant magneto-resistive effect element.
2. Description of the Related Art
A so-called merge type combined magnetic head, which results from combining an induction type write magnetic head and a read magnetic head using a magneto-resistive effect (i.e., magneto-resistive effect type head), is employed as a high-density magnetic recording device such as a hard disk drive at present.
As a magneto-resistive effect element (MR element) for use in a magneto-resistive effect type head comprising a read magnetic head located on the lower layer of the combined magnetic head, there has recently been employed a giant magneto-resistive effect element (GMR element) having higher sensitivity.
A GMR element, which is now commercially available on the market, is used in the mode called a xe2x80x9cCIPxe2x80x9d (Current In Plane) mode in which a sense current for sensing a magneto-resistive effect flows in the direction parallel to a film plane of a lamination layer film of a GMR element.
In the magnetic heads for use as a HDD (hard disk drive), there is the main stream in which a magneto-resistive effect type head including upper and lower shields on the CIP element operable in this CIP mode is used as a read magnetic head of a lower layer.
In order to achieve a recording density higher than 100 gigabits/inch2, a magneto-resistive effect element has to have a high linear density so that the magneto-resistive effect element has to be microminiaturized much more.
However, according to the CIP type MR element which is used in the above-mentioned CIP mode, it becomes more difficult to dispose a GMR element between the upper and lower shield films having a film thickness of less than 100 nanometers while the upper and lower shield films and the GMR element are being insulated from each other.
So far it has been examined that a CPP type GMR element, which is used in the mode called a xe2x80x9cCPPxe2x80x9d (Current Perpendicular to the Plane) in which a sense current flows in the direction perpendicular to a film plane of a lamination layer film of a GMR element and a CPP type TMR (tunneling magneto-resistive effect) element are used as the MR element.
Since the CPP type GMR element uses the shield films as electrodes, the shield films and the GMR element need not be insulated from each other. Hence, the above-mentioned problem of the insulation between the upper and lower shield films and the GMR element can be solved basically.
Further, because the CPP type GMR element has an increased area in which it comes in contact with an electrode film made of a metal film having an excellent thermal conductivity, the CPP type GMR element has a characteristic in which an electromigration is difficult to occur therein at a remarkably high current density as compared with the CIP type GMR element. Therefore, it is considered that the CPP type GMR element is able to realize a narrow magnetic gap and a narrow track width which are the requirements of the high-density recording magnetic head.
When the MR element is used in the magneto-resistive effect type head, the MR element has the upper limit of the resistance value from viewpoints of a thermal noise, an ESD (Electric Static Discharge), a resonance in a read IC and a write IC and so forth. Further, the MR element has the lower limit of the resistance value from a viewpoint of an output.
Then, in the area in which the recording density falls in a range of from 100 to 200 gigabits/inch2, when the CPP type TMR element is used as the MR element, the resistance of the MR element has to be decreased. When the CPP type GMR element is used as the MR element, the resistance of the MR element has to be increased.
In order to increase the resistance of the CPP type GMR element, it is proposed that a high resistance layer should be inserted into the lamination layer film of the GMR element, for example.
However, when the high resistance layer is inserted into the lamination layer film of the GMR element as described above, if a hard magnetic material having a conductivity, such as a metal is used as a hard film (hard magnetic film) to stabilize the magnetization of the GMR element, then a sense current is shunted into the hard film so that a current, which is flowing through the GMR element, is decreased. There then arises a problem that the output of the GMR element is lowered.
For this reason, in order to insulate the GMR element and the hard film from each other, there can be considered a configuration in which a GMR element and a hard film are bonded to each other through an insulating material or a configuration in which an insulating or high-resistance hard magnetic material is used as a hard film.
However, from a view point of the cost of a material, it is to be desired that a hard magnetic material having a conductivity, which can be manufactured comparatively inexpensively, should be used as a hard film. Furthermore, in order to sufficiently stabilize a magnetization of a magnetization free layer of a GMR element, it is to be desired that the hard film should directly be bonded to the GMR element.
In view of the aforesaid aspect, it is an object of the present invention to provide a giant magneto-resistive effect element capable of producing a high output and a high resistance and which can cope with a high recording density and a magneto-resistive effect type head, a thin-film magnetic memory and a thin-film magnetic sensor, each of which includes this giant magneto-resistive effect element.
According to an aspect of the present invention, there is provided a giant magneto-resistive effect element comprising a lamination layer film including a ferromagnetic film, a nonmagnetic film and an antiferromagnetic film and in which the ferromagnetic film includes a magnetization free layer and a magnetization fixed layer and a current is restricted by an upper electrode and a lower electrode so that the current flows to the direction perpendicular to the film plane of the lamination layer film, wherein the lamination layer film is laminated including a high-resistance layer, a hard magnetic film made of a conductive hard magnetic material and an insulating layer are directly bonded to respective outsides of the lamination layer film along its width direction and the hard magnetic film is shifted from the high-resistance layer and bonded nearer the magnetization free layer.
According to another aspect of the present invention, there is provided a magneto-resistive effect type head including a giant magneto-resistive effect element comprising a lamination layer film including a ferromagnetic film, a nonmagnetic film and an antiferromagnetic film, the ferromagnetic film includes a magnetization free layer and a magnetization fixed layer and a current is restricted by an upper electrode and a lower electrode so that the current flows to the direction perpendicular to the film plane of the lamination layer film, the lamination layer film is laminated including a high-resistance layer, a hard magnetic film made of a conductive hard magnetic material and an insulating layer are directly bonded to respective outsides of the lamination layer film along its width direction and the hard magnetic film is shifted from the high-resistance layer and bonded nearer the magnetization free layer, wherein upper and lower magnetic shields are disposed so as to sandwich the giant magneto-resistive effect element through a gap film made of a nonmagnetic conductive material, the gap film and the magnetic shields constitute the upper electrode and the lower electrode and the upper electrode, the lower electrode and the lamination layer film are connected to each other electrically.
In accordance with further another aspect of the present invention, there is provided a thin-film magnetic memory including a bit line, a word line and a giant magneto-resistive effect element comprising a lamination layer film including a ferromagnetic film, a nonmagnetic film and an antiferromagnetic film and in which the ferromagnetic film includes a magnetization free layer and a magnetization fixed layer and a current is restricted by an upper electrode and a lower electrode so that the current flows to the direction perpendicular to the film plane of the lamination layer film, the lamination layer film is laminated including a high-resistance layer, a hard magnetic film made of a conductive hard magnetic material and an insulating layer are directly bonded to respective outsides of the lamination layer film along its width direction and the hard magnetic film is shifted from the high-resistance layer and bonded nearer the magnetization free layer, wherein a memory cell including the giant magneto-resistive effect element is disposed so as to oppose to a crossing between the bit line and the word line.
In accordance with a further aspect of the present invention, there is provided a thin-film magnetic sensor including a giant magneto-resistive effect element comprising a lamination layer film including a ferromagnetic film, a nonmagnetic film and an antiferromagnetic film, the ferromagnetic film includes a magnetization free layer and a magnetization fixed layer and a current is restricted by an upper electrode and a lower electrode so that the current flows to the direction perpendicular to the film plane of the lamination layer film, the lamination layer film is laminated including a high-resistance layer, a hard magnetic film made of a conductive hard magnetic material and an insulating layer are directly bonded to respective outsides of the lamination layer film along its width direction and the hard magnetic film is shifted from the high-resistance layer and bonded nearer the magnetization free layer, wherein upper and lower magnetic shields are disposed so as to sandwich the giant magneto-resistive effect element through a gap film made of a nonmagnetic conductive material, the gap film and the magnetic shields constitute the upper electrode and the lower electrode and the upper electrode, the lower electrode and the lamination layer film are connected to each other electrically.
According to the arrangement of the above giant magneto-resistive effect element of the present invention, since the lamination layer film is laminated including the high-resistance layer and the resistance of the lamination layer film of the giant magneto-resistive effect element can be increased by the high-resistance layer, this giant magneto-resistive effect element becomes able to cope with high recording density.
Further, since the hard magnetic film and the insulating layer are directly connected to the respective outsides of the lamination layer film and this hard magnetic film is shifted from this high-resistance layer and bonded nearer the magnetization free layer, the insulating layer is directly bonded to at least part of the high-resistance layer, i.e., the opposite side of the magnetization free layer, and the current can be prevented from being shunted to the hard magnetic film by this insulating layer so that the current can flow in the high-resistance layer. Thus, the output can be prevented from being lowered by the loss of the current shunted and this giant magneto-resistive effect element can obtain a high output. Moreover, since the loss of the shunted current is restrained and the current flows in the high-resistance layer, it is possible to increase the effective resistance of the lamination layer film relative to the current.
Furthermore, since the hard magnetic film is directly bonded to the magnetization free layer, the magnetic field from the hard magnetic film strongly acts on the magnetization free layer with the result that the magnetization direction of the magnetization free layer can be stabilized. As a consequence, the operation, i.e., resistance change of the giant magneto-resistive effect element can be stabilized.
According to the arrangement of the above-mentioned magneto-resistive effect type head of the present invention, since this magneto-resistive effect type head includes the above giant magneto-resistive effect element, the output can be restrained from being lowered due to the loss of the shunted current and the high output can be obtained. Therefore, there can be configured the magneto-resistive effect type head which can increase its output. Furthermore, it is possible to decrease the sense current necessary for obtaining the same output.
Further, according to the arrangement of the above-mentioned thin-film magnetic memory of the present invention, since the memory cell includes the above-described giant magneto-resistive effect element of the present invention, the output can be restrained from being lowered due to the loss of the shunted current and the giant magneto-resistive effect element can produce the high output. Thus, even when the amount of the current flowing in the word line and the bit line, for example, is decreased as compared with the related art, it becomes possible to write or read information in or out of the memory cell in this thin-film magnetic memory.
According to the arrangement of the above-mentioned thin-film magnetic sensor of the present invention, since this thin-film magnetic sensor includes the above-described giant magneto-resistive effect element of the present invention, the output due to the loss of the shunted current can be restrained from being lowered and the high output can be obtained. Thus, even when the change of the external magnetic field is small, it is possible to configure the thin-film magnetic sensor which can produce the high output. Furthermore, it is possible to reduce the sense current necessary for obtaining the same output.